Evaluation of the Soil Quality on the Reclaimed Lignite Mine Land in West Macedonia, Greece

The West Macedonia Lignite Centre (WMLC) is a complex of surface mines that produces annually 45 Mt of lignite and excavates more than 280 Mm(3) of earthy materials. After 60 years of operation, WMLC occupies 16,000 ha. Up to now, 4,000 ha of mine spoils have been reclaimed; sloped surfaces have been reforested and horizontal surfaces are rented as farmland. Based on the environmental permits that are in force, WMLC conducts systematically soil sampling and lab analyses for determining quality characteristics of reclaimed soils that concern both soil fertility and contamination control. According to the results of lab analyses carried out so far, reclaimed soils are characterized by an alkaline pH and normal electrical conductivity values. Their particle size distribution classifies them from moderately coarse to fine soils. A large number of samples exhibit high CaCO3 content, while organic matter content is high in samples collected from reclaimed mine spoils where lignite seams of low calorific value have been dumped. Cation exchange capacity is high, mainly due to high concentrations of iron in assimilable form. Regarding the concentrations of nutrients, these exhibit a wide variation depending on the element and sampling depth. Sufficient concentrations of the exchangeable cations K+, Ca2+ and Mg2+ have been determined in the majority of the soil samples. Phosphorus concentrations are below the generally accepted availability level of 20 mg/kg. Heavy metals concentrations are below the screening values determined by the Dutch Soil Pollution Act with the exception of Nickel, which often exhibits concentrations higher than the intervention value of 210mg/kg. Chromium concentrations are also high but do not exceed the intervention value of 380mg/kg. Iron is the only metal that exhibits systematically higher concentrations in soil samples collected from the reclaimed mine spoils than in soil samples collected from areas of West Macedonia region that have not been disturbed by lignite mining operations. (C) 2015 The Authors. Published by Elsevier B.V.